This invention relates generally to man-machine interactive methods and apparatus; and more particularly, to the mapping of an electronic disturbance on an input surface.
It is well known to provide a resistive/capacitive touch-mapping method and apparatus wherein the location at which an individual touches a display surface can be determined by an automatic electronic process. A typical application is a cathode ray tube touch terminal in which a human operator enters information to a data processing system according to the location at which the operator touches a terminal display screen. Other applications include a position indicator, switch panel and touch tablet.
One such system is described in U.S. patent application Ser. No. 452,024, assigned to the assignee hereof. That application describes a touch-responsive method and apparatus in which an operator touch is mapped by measurement of the change in current drawn by the touch through a resistive panel of known spatial resistive characteristics. In one embodiment, the apparatus employs a single electrode element along each side of a rectangular panel surface; and this electrode configuration creates a nonuniform electric field pattern in the panel in response to an applied source signal. The field nonuniformity introduces complexities and mapping errors in the mapping function because it requires the apparatus position measurement system to perform more extensive and complex position calibrating and determining procedures. In a further embodiment, the apparatus of the U.S. patent application Ser. No. 452,024 relates to a touch-responsive panel having point corner electrodes for improving the mapping accuracy in the panel corner regions.
Accordingly, objects of this invention are a touch-mapping method and apparatus with improved touch-mapping capabilities which is relatively easy to implement on a commercial basis, which operates with high accuracy and high reliability, and which is relatively low in cost and thereby suited for varied touch-mapping devices. A further object of the invention is a touch-sensitive panel having improved linear mapping properties.
Other objects of the invention will in part be obvious and will in part appear hereinafter.